Rocks and the Rock Cycle

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Transcript of Rocks and the Rock Cycle

Essential Questions: 1.) How are rocks formed?2.) How are rocks classified and identified?3.) What are the differences between the three types of rocks?What is a rock?Igneous Rocks!Sedimentary Rocks!Metamorphic Rocks A rock is a mixture of two or more mineralsEQ 4: How do igneous rocks form?EQ 5: How are igneous rocks classified and identified?EQ 6: How do sedimentary rocks form?EQ 7: How do you classify and identify sedimentary rocks?EQ 8: How are Metamorphic rocks formed?EQ 9: How are Metamorphic rocks classified and identified?Rocks and the Rock CycleBiotiteQuartzK-FeldsparThe three rock types:Igneous:derived from latin word 'ignis' meaning fire. Igneous rocks are formed through cooling and solidification (to become solid) of magma or lava. Sedimentary: formed from the deposition (accumulation) of material (either on earth’s surface or in bodies of water).Metamorphic: a transformation of existing rock types through heat and pressure.IgneousSedimentaryMetamorphicHow are these rocks related?Weathering, Erosion, Compaction, Cementation, Melting, Pressure, Heat, Cooling, and more.You can actually alter and change these rocks!For example: you melt a sedimentary rock it can now be considered an igneous rock!The Rock Cycle:Igneous rocks are formed through cooling and solidification (to become solid) of magma

or lava.What's the difference between magma and lava?MAGMA = INTERIOR (Inside of the Earth)LAVA = EXTERIOR (Outside of the Earth)Why do the differences of magma and lava even matter?In order to determine what type of igneous rock there is depends on:

Where it was formed.What materials make it up.Three ways to classify igneous rocks:Composition:based on the materials that make them upFelsic - Made from lightly colored minerals, so you get a lightly colored rock.Minerals found: Quartz and Feldspar

Mafic - Made from dark colored minerals, so you get a dark colored rock. Minerals found: Biotite and Horneblende

Mafic and Felsic - Light and DarkMinerals found: Horneblende and QuartzFelsicMaficWhat about this one?Mafic or Felsic?Diorite is Mafic and Felsic!Where they form:Intrusive (Magma):Cools slowly inside the earth (a lot of time to grow = larger crystals)

Extrusive (lava):Cools quickly on surface of the earth (little time to grow = small or no crystals or even airholes).IntrusiveExtrusiveTextures of the rocks:Pegmatitic: (Intrusive) Very large crystals Phaneritic (Intrusive)- large crystals you can see.Porphyritic (Intrusive and Extrusive) - Large and small crystals.Glassy (extrusive) - looks like glass.Aphanitic (Extrustive) - Can’t see any crystals.Vesicular (extrusive) - holes formed from trapped gas.PhaneriticGlassy

Aphanitic

VesicularPorphyriticINTRUSIVE:EXTRUSIVE:

Formed from the deposition of materialMade up ofbroken or weathered pieces of rock.What are some materials that these rocks are formed from?Pebbles, Sand, Clay, Shells, Dead Plants and Animals, Calcite, Halite, and Gypsum.Sedimentary Rocks:SandPebblesDead PlantsHow do all of these materials create a rock?Lithification: this is compaction and cementation of these materials.MountainOceanBrecciaConglomerateArkoseSandstoneShaleClassifying Sedimentary Rocks:

1.) Clastic - Made of both rounded and jagged rock fragments.

2.) Chemical - Made of precipitates or evaporates(i.e. when bodies of water contain dissolved sediments, minerals fall out of solution through evaporation or chemical means).

3.) Organic - Made of once-living things (plants and animals).Composition:Textures:1.) Cemented - means I can see the fragments(Sand, silt, pebbles, ect. )

2.) Microcrystalline - Can’t see any fragments

3.) Skeletal - means I can see the organisms.(Shells, plants, ect.)Formative Environment:1.) Near shore (Beach) - Formed from Sand, Silt, Clay, Pebbles, and Shells.

3.) Land - Formed in caves or from decaying plants or animalsEX: Peat, Lignite, Bituminous Coal. Cave rocks such as travertine.

4.) Lakes and Lagoons - From evaporationEX: Rock Salt and Rock GypsumSince it is difficult to distinguish which sedimentary rocks have a CHEMICAL COMPOSITION I have provided you with the minerals that have this composition:Crystalline LimestoneRock GypsumHave fun and Good Luck!What does metamorphosis mean??Change!!Definition:Rock that has been

CHANGED by heat and pressure. (not melted)GraniteGneissThe minerals formed into stripes!Where can you get enough heat and pressure to metamorphose a pre-existing rock?Dynamic MetamorphismThermal MetamorphismTwo types of Metamorphism:

Thermal:When buried rocks come in contact with magma and high heat, the rock ‘bakes’ and re-crystallizes. It does NOT melt. If it melted and then crystallized it would be considered what type of rock?Two types of metamorphic rock:

Foliated:Mineral grains have been flattened into parallel bands or stripes.

Granite forms...EpidoteMarbleQuartziteAnthracite CoalSlatePhylliteGneissSchistMeltingPegmatiticHigher/further from ocean = larger, more jagged particlesCloser to ocean, more rounded smaller particlesWhy are the sediments smaller and rounder closer to the ocean?Remember: Sedimentary rocks are formed from weathering and erosion. Once the rock is broken down (weathered)It can be transported/moved easier by wind or water (erosion)Will be deposited down hill.Once it it there is becomes buried by other sediments.*A rock with a cemented texture will always be clastic!